Field of the Invention
The present invention relates to an image forming apparatus for adjusting an image forming position based on read data of a test chart.
Description of the Related Art
When an image is printed on a sheet, an image forming apparatus first forms the image on the sheet and fixes the image by heat in a fixing unit. At that time, the sheet shrinks by heat from the fixing unit. Thus, print positions may respectively deviate in a main scanning direction and a sub scanning direction of the sheet.
An image forming apparatus described in U.S. Pat. No. 7,760,370 output an adjustment pattern in which reference images for alignment are formed at four corners on a sheet to correct an image forming position of the sheet. The adjustment patterns are printed on both of a first surface and a second surface different from the first surface of the sheet.
A user places the sheet output from the image forming apparatus on a scanner. The user causes the scanner to read the adjustment pattern on the first surface of the sheet. Subsequently, the user turns the sheet on which the adjustment pattern is formed on the scanner and causes the scanner to read the adjustment pattern on the second surface of the sheet. The image forming apparatus adjusts the image forming position of the first surface and the image forming position of the second surface using the read data of the adjustment pattern printed on the first surface of the sheet and the read data of the adjustment pattern printed on the second surface of the sheet.